<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .con{
            display: flex;
            width: 1200px;
            border: 1px solid red;
            /* 让子元素超出部分换行 */
            flex-wrap: wrap;
            /* 第一行在下面   */
            /* flex-wrap: wrap-reverse; */
        }
         .item {
            width: 200px;
            height: 300px;
            border: 1px solid rebeccapurple;
        }
    </style>
</head>
<body>
    <div class="con">
        <div class="item">
            1
        </div>
        <div class="item">
            2
        </div>
        <div class="item">
            3
        </div>
        <div class="item">
            4
        </div>
        <div class="item">
            5
        </div>
        <div class="item">
            6
        </div>
    </div>
</body>
</html>